Motor vehicles include an engine block to which are mounted several belt driven devices. These may include a power steering pump, generator, air conditioning compressor, air pump, and an engine coolant pump, also referred to as a water pump. These devices are powered by a serpentine drive belt which is driven by the crankshaft pulley. The belt wedges neatly into the different pulley grooves, and uses the tension and friction to turn the pulleys attached to the devices. The belt may be subject to significant length change, especially stretch, causing the belt to undesirably loosen with use. The belt-driven accessories may also be removed and remounted in a slightly different position during maintenance causing a slackness in the belt. On the other hand, the belt cannot be too tight or it will put too much pressure on the device bearings and cause them to wear prematurely. As such, proper belt tensioning is very important to the proper functioning of the motor vehicle.
Generally, water pumps have a housing secured to the engine block and a pump shaft rotatably supported by a ball or roller bearing within the pump housing. An impeller is fixed to the inner end of the pump shaft, while the outer end of the pump shaft extends out of the housing and has a pulley fixed thereto. The crankshaft driven belt rotates the pump shaft pulley which in turn drives the pump shaft and impeller.
Because the belt is subject to length change, and because the proper tension is very important, a tensioner is desirable to maintain proper tension in the belt so as to maintain proper frictional contact between the belt and the various pulleys that it engages. Further, in racing vehicles, because of the vigorous driving conditions, the belt will wear and stretch considerably faster. Additionally, the frequency of maintenance, including disassembly and reassembly and dismounting and remounting of the various engine parts, is much greater than that of a conventionally-used vehicle.
Conventionally, belts in a vehicle may be adjusted by loosening the support for the alternator and moving it back and forth to tighten or loosen the belt. A typical adjustment procedure for this method is to first loosen the adjustment fastener on the slotted alternator support. Then, a pry bar must be wedged between a strong part of the engine and the alternator. One must then pull on the pry bar to move the alternator housing in a direction and tighten the belt. Lastly, the adjustment is rechecked. Other systems use a spring-mounted idler pulley to provide tensioning.
Thus, the adjustment of the belt is a difficult, cumbersome, and often time consuming task. For conventionally-used vehicles, the inability to quickly and easily adjust the tension of the belt is not of critical importance. However, with racing vehicles, the time and effort required to adjust the belt is very important because of the frequency of adjustments required and the time pressures of a pitstop. Thus, a device which allows quick and easy adjustment of the tension of the drive belt is desirable.
Also, the current mechanisms used for the adjustment of the drive belt may hinder other maintenance work on the engine. For conventionally-used vehicles, the extra time for maintenance because of this is not so important. However, with the frequency of maintenance repair work to racing vehicles, this time and effort is of great importance. Thus, a device which further eases maintenance to the vehicle is highly desirable.
One additional method of belt tensioning that is currently used, particularly in racing vehicles, where there is typically a separate belt for the alternator from the water pump, is moving the entire water pump to adjust the tension of the drive belt. In such a device, the water pump's mounting holes which attach to the engine block are elongated to allow for the repositioning of the water pump to adjust the tension of the drive belt. However, the readjustment of the water pump is clumsy because of having to move the entire water pump. Furthermore, frequent repositioning of the gaskets which are placed between the water pump housing and the engine block leads to leakage from the gaskets.
Accordingly, a need exists for a drive belt tensioning mechanism that allows quick and easy adjustment of the drive belt, that does not hinder or slow down further maintenance to the vehicle, that is cost effective, and one that is easily installed and operated.